Combustion control



March 7, 1939. R. AIFORESMAN ET AL 2,149,393

COMEUST I ON CONTROL Filed June 25, 1936 I 3 Sheets-Sheet l WITN ESSES:

INVENTOR -ROBERT H. Fame-s MHN. andv Day/7w J. MOSSHHRT v GED M I ATTORNEY 3 Sheets-Sheet 3 R. Av FORESMAN ET AL COMBUSTION CONTROL Filed June 25, 1956 March 7, 1939.

INVENTORS ROBERT E. FbREsMn/v and Dog/ n0 J. MOSSH/TRT. I V ATTORNEY v WITN ESSES; A

Patented Mar. 7, 1939 PATENT, OFFICE COMBUSTION CONTROL Robert A. Foresman, Prospect Park, and Donald J. Mosshart, Springfield, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 25, 1936, Serial No. 87,138

8 Claims.

Our invention relates to control means for apparatus supplying gaseous medium to a bed offering variable flow resistance and it has for an object to provide said means so constructed and arranged that the rate of flow ofgaseous medium is held substantially constant irrespective of changes in flow resistance of the bed.

A further object of our invention is to provide a duct construction for supplying gaseous medium, such as air, from a region toa bed offering variable flow resistance, the duct construction including an orifice and a throttle arranged between the orifice and the bed, the throttle including an element movable in response to change in differential pressure across the orifice due to change in flow. resistance of the bed. A further object of our invention is to provide a plurality of duct constructions for'supplying gaseous medium, such as air, from a region to different areas of a bed such that eacharea will receive gaseous medium substantially at the constant rate even though the flow resistance of each area may vary.

' These and other objects are efiected by our invention as will be apparent from the following.

description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a longitudinal sectional view of a stoker showing our air control devices applied thereto; I

Fig. 2 is a transverse sectional view taken along the line 11-11 of Fig. 1;

Fig. 3 is a diagrammatic view showing a series of our control devices for a tuyere row;

Fig. 4 is a sectional view of a simplified form of device; and,

Fig. 5 is a View similar to Fig. 4 but incorporating a float. H

Referring now to the drawings more in detail, in Fig. 1, we show a stoker, at in, forming the bottom of acombustion chamber I I and having a plenum chamber or air box 12 arranged therebelow. The plenum chamber is supplied with air through aduct I3 by the usual means, it being the intention that the plenum chamber pressure shall be maintained substantially constant and that the blower furnishing the duct l3 with air shall have adequate capacity for all operating conditions of the stoker.

- The stoker includes the usual retorts l4 and intervening ,tuyre rows 15 and outside side wall tuyres l6. ,Air channels ll are arranged below the tuyre rows ['5 and the side wall tuyeres l6. Transverse plates I8 preferably divide each channel ll into a plurality of sections I9, 20, 2|, and 22 supplied with air by duct constructions or devices 23, 24, 25, and 26 for each tuyre row. As shown in Figs. 1 and 2, each tuyere row air channel has connected thereto a group of devices 23, 24, 25, and 26, the devices being arranged at different levels on account of inclination of the stoker; and devices 23, 24, 25, and 26 of all the tuyeres are, respectively, arranged in transverse rows, the row of devices 26 being at the front of the stoker and the other rows 25, 24, and 23 being arranged successively back thereof.

. Each of the duct constructions 23, 24, 25 and 26 includes a duct element 28 and a chamber 30 at its inlet end and each chamber 30 has a body of liquid 3| therein and an orifice 32 provides for the admission of air thereto from the plenum chamber l2, the orifice being arranged above the level of liquid. Gaseous medium, such as air, admitted by the orifice 32, passes through a variable throttle area 36 before entering the duct element 28, the purpose of the orifice being to provide a differential pressure for controlling the throttle area, the arrangement being such that the throttle area is varied to compensate for variations in fiow resistance of the region supplied by the duct construction.' As shown in Figs. 1, 2 and 3, the orifice 32, discharges into a secondary chamber 29 formed by a downwardly-directed tubular structure or nozzle 33 whose Y horizontally-disposed lower end 34 cooperates with a float sustained by the liquid to provide the circumferen tially-extending throttle area 36."

The level of liquid 3| in each tertiary chamber 30 is determined in the first instance by an over flow'device 38 open at the top to form a well or primary chamber 39 exposed to plenum chamber pressure. Thus, it will be seen that each device has a body of liquid arranged in a monometric manner, that is, one portion is arranged within the chamber 30 and subject to secondary pressure and the other portion is arranged in the well .and subject to plenum chamber pressure. As may be seen from Figs. 1 and 3, each overflow 38 is provided with means, for example, a tube arrangement 40, which is adjusted by any suitable means 4| for the purpose of adjusting the quantity of liquid and the level thereof for each device. v

In the preferred form of apparatus shown in Figs. 1,2, and 3, the flows of air in each device between the orifice 32 and the throttle 36 and from the latter, are in such directions that, with thefloat, 35, there is little, if any, liquid entrainment, this particular arrangement being specifically disclosed and claimed in the application of R. A. Foresman, Serial No. 84,405, filed June 10, 1936.

As air entering through an orifice 32 is discharged downwardly by the nozzle-like structure 33 against the float 35 and the air then travels upwardly through the duct tothe" st'oker, it will be apparent that the float 35 acts as a float valve throttling the discharge of the nozzle and providing a throttling area 36 between the float and the" nozzle, or a throttle as already pointedoout. The float 35 is supported by the body of waterwithin the device; and, as already pointedout, the body. of water associated with each device isdisposed in a manometric manner so that partthereof is subject to primary pressure Pi' and a part is arranged within the device so as to be subjected to secondary pressure P2, as may be seen-from the duct 7 construction 24 in Fig. 3. As a matter of fact, the

body of liquid in the chambers 30 of'Figsr 1, 2,

and 3 is subject to bothsecondary and tertiary pressures, P2 and-P5, that is; the" pressures at the upstream and downstream sides of the throttle area 36.-

' s Changes in the pre's'sure'differential across the orifice. 32 causes' the liquid level within the chamber 30 to'ri se or fall to vary the throttle area, anincrease-in the differential causing the liquid to rise and vice versa. Assuming that this differential, (P 1 P2) increases, then the float 35 rises; reducing the throttle mass; and, inconsequence, a second pressur e' differential (PzP's) the difference between secondary and tertiary pressure, is set up across the-throttle 36 and which imposes the di fference of primary andtertiary pressure (Pi-Pa) upon the water within the device, causing afurther rise of thewater thereinand a; further lift of the float.

Thus,.-itwill beseenthat the float 35 and the manometric body of liquid-.supporting: it'comprise the "lower and-movable element .of the throttle; suchelement being inherently capable of providing a force acting inropposition tothe force of-= the pressure at the-inlet side of the orifice, whereby the movable elementdnaybe moved by the variousforces acting thereon to difierent positions'to restoreapproximately the rate of' flow of air through the device in case ofvariation in-fuel bed resistance. 'With the floatin equilibrium, the forces'thereonare the upwardly acting lift: force of the'-water,-it being rememberedthat thefloat is-positioned primar-; ily by the extent of rise or fall of the manometric leg of-watersustaining it, the downwar dlyacting static: secondary pressure P2 and: the impact of theair stream passing through the throttle area fromthe secondary to the tertiary pressure regionsp'suchimpact:being a function'of P2 minus P33 Aside from the manner of respo-nseof the m'anometriccolumn of liquid-to the various pres-; sures, z-res'ulting in movement of such column, and, therefore, of the fioat, the'effect 'of-the'lift of the liquid; on the float is,'of course, also a function-of its shape, that is, its displacement; Furthermore, an 'additional "control of the" reac-' tio'ns 'of eachdevice 'may be obtained by varying the initial {value of the throttle area} this providing an initial pressure differential between secondary and tertiary pressures (Pa-Pg) before th dvi'ce begins :to' res on to changes in theTate-o'f'air flow; "The upward and downward forces acting o'n' the' float 35 are br'ough't'into balance byproportionirig the displacement of the float-and the-area subject to im'pact'and static air pressure. 5 Once the forces arebalanced, the

lower movable throttle element, comprising the liquid and the float, functions to maintain a substantially constant rate of air flow through the device irrespective of changes in fuel bed resistance of the region or area supplied thereby. In general, the lower movable throttle elements have liquid-sealed pressure abutment faces subject to pressures at the inlet and exit sides of the orifice, such pressures providing opposed forces acting on the element to afford movement thereof and to vary the throttle area, and the" throttle is inherently capable of providing a gravity force; which, with the force due I to the pressure atthe exit side of the orifice,

balances theforce due to the pressure at the inlet side of the orifice; and, while these are the main forces acting in opposition to efiect equilibrium of. the movable element, nevertheless, there may be other forces exerting an effect on the movable element, such forces being that due to: the tertiary pressure and the, impact force effective in the arrangement shown in Fig. 1.

It is desirable to. maintain predetermined quantities or levels of liquid in each device; this being-determined by appropriate adjustment of the'overfiows in the manner already indicated. It is also necessary to replenish each device with water, that is, to keep the overflows thereof filled to the point of overflow. Accordingly, in Figs. 1, 2, and 3, we show an arrangement for eifecting this purpose. Each transverse group of chambers 30 are connected in series by means of the nipples 5i] and cooperating couplings 5|, the intermediate chamber 39- extending below the others to provide a hopper 52 for a purpose to be immediately pointed out. If water is supplied by means of the inlet conduit 53, as shown in Figs. 1 and 3, to one of the devices 26, it will be apparent-that all of the devices of that group will be supplied with Water through the nipples and the couplings. -Furthermore,'a single overthrow is adequate to maintain a desired level of liquid in that group of devices.

-Theconduit connections 54, 55, and 56 from the overflow of a preceding transverse group, beginning with the group'26, and one of the intermediate chambers of the next group provide for a cascade connection of the groups so that arsingle waterasupply connection 53 and a single drain conduit 51, for the last transverse group, sufllce to keep all of the devices adequately supplied'with water.

There is also shown suitable means for flushing out all of the devices, this means being more particularlydescribed and claimed in the application of D. J. MossharaSerial No. 85,861, filed June 18, 1936, such means comprising drain branches 58 associated with the hoppers or sumps 52 of intermediate devices, as already pointed out, the drain branches being connected to a drain pipe 59 and each drain branch having a valve 60. As may be seen-from Fig. 2, opposite water jets v62 are associated with the outermost chambers 30, the jets being supplied by water pipes 63 having'valves 64. With this arrangement, if the valves 66 are opened to the desired extent, and the jets 62 are rendered effective, it will be apparent that'such jets will entrain liquid and solid media from the chambers from each side toward the central hopper, this being made possible by alignment of the nipples and couplin'gs of each group of devices whereby the jet streams will be directed there'along from each side and toward the hopper, and media will drain 2,149,393- rrt the hopper or hoppersthrough the conduit 59. g

While it is intended that the pressure, P1, of thechamber orwindbox shall be maintained substantially constant, it may be necessary to effect changes in flow of air'through the various devices to take'care o-f differentload conditions. Accordingly, each orifice 32 has associated therewith a 1 Valve or gate 65 for varying its area, the gate valves being connected to operating rods 66, whose lower'ends'are pivotally connected to cranks 61 of the crank shaft 68. The crank shafts 68 have cranks 69, each provided with a plurality of openings "Ill arranged at different radial distances from the axis of the crank shaft 68, and links H, having turnbuckles 12, have their ends pivo'tally connectedto the cranks 69, each link H being suitably adjusted in length and connected to 'opening s'to secure the desired relative extent of operation of the gate valves of the different transverse groups of air control devices. The interconnected arrangement of crankshafts may be operated by manual or automatic means, for example, the loaderesponsive combustion control device, as shown at H, this device being connected by, means of linkage to the'first of the crank shafts 6B. As shown, the linkage at 15 embodies a link 16 having a turnbuckle TI and such link being pivotally-connected to the first crank 59 and associated with one) of the openings 10 therein. From this, it will be apparent that all of the gate valvesmay bechanged relatively to the load responsive device 14 by suitable connection of the link 16 with the first crank 10; and, as already pointed out, the gate valves .of the devices of the various groups may all be adjusted to the same extent or they may be adjusted todifferent extents, the capacity for relative variation being provided for by the links ll of variable length and the connections of the ends thereof to any of the openings lll in the cranks 69.

. In Fig. 4, there is shown a simplified form of duct construction, which differs over that already described mainly in that the nozzle is arranged between the chamber 30 and the duct 28 rather than between the orifice and the chamber, as in Figs. .1, 2 and 3. In the modified form, the duct 28 has a tubular structure lzadepending within the chamber 30, the latter having an orifice 32 circumferential throttle area 45 and duct 28.

A well or primary chamber 39 exposed to theplenary or windbox pressure has its bottom portion connected to the bottom portion of the chamber 30 by an opening 43, whereby the charmbers 39 and 30 provide a manometric chamber. A suificient quantity of liquid 3| is placed in the chamber 30 and in the well 39 to keep the opening 43 submerged under all conditions. Accord- 'ingly, there is provided a manometric arrangei ment of liquid, the first part being in the well 39 and exposed to plenary or primary air pressure P1, and a second part being in the chamber 3!! and subject to secondary pressure P2. The level of liquid 44 cooperates with the lower end 42 of the tubular element 32a to provide a circumf-erentially-extending throttle area 45. As before,

the change in differential pressure across the orifice 32 incident tochange in fiow resistance of the region supplied by the duct 28 brings about change in liquid level to vary the throttle area so as 130;; Compensate for change in fiow resistance of the region. q

In Fig. 5,- there is shown a modified form simi lar to'Fig. 4 except that a float 46 is sustained byv the liquid and it cooperates with the tubular element to define the'annular orifice area 45a, which changes with'changes in level 44a of the liquid. A

' From the foregoing, the effect and operation of our improved apparatus will be apparent. First of all,'there is a region of variable flow resistance, such as a fuel bed, to "be supplied with gaseous medium such asair, and the object of the invention is the provision of one or more ducts or devices for supplying gaseous medium from a chamber under suitable pressure to the region, each duct or device including arrangements to maintain the flow rate substantially constant irrespective of changes in flow resistance of the particular region supplied. The arrangements making this result possible comprise primarily an inlet orificefor admitting gaseous medium from the chamber to the duct or device and a throttle arranged in the duct and following the device, the throttle including fixed and movable elements defining a variable throttle area and the movable element being-constructed and arranged to provide pressure abutment faces subject to the pressures at the inlet and exit sides of the orifice and to provide a force, in addition to the pressure forces, and all of the forces being necessary to produce a condition of equilibrium of the movable element. The additional force just referred to is preferably inherent in the movable element, that is, it may be a gravity force which is made available by the construction and arrangement of the movable element. The movable element comprises a body of liquid and a manometric chamber to give form and to confine the bodyin such a way that a gravity force is made available for the purpose just indicated, and the liquid so disposed presents sealed pressure abutment faces subject to pressures at the inlet and exit sides of the inlet orifice, an equilibrium condition being produced by the gaseous pressure forces acting on the-abutment faces and the gravity force acting on the body, all of these forces cooperating to determine movement of the movable body element to that necessary to restore equilibrium following the occurrence of an unbalanced condition. The additional force afforded by the gravity effect finds its counterpart in many kinds of control apparatus, that is, in the present invention, the movable throttle element is so constructed and arranged that it inherently provides a balancing force cooperating with the gaseous pressure forces to produce an equilibrium condition; and, when an unbalanced condition occurs, as by change in differential pressure, the movable element moves in consequence, but such movement is affected or determined by the gravity force, and, as movement of the movable element occurs in such a direction as to tend to restore the differential pressure, the gravity and orifice exit side pressure forces changing in opposite directions operate to restore the equilibrium condition, at which time the gravity and exit side pressure forces balance the inlet side pressure force andthe differential pressure is'brought backapproximately to its normal value.

By having a multiplicity of ducts or devices of the character'just'indicated and connected to different regions of the fuel bed, and as each duct or device includes contrivances to maintain the rate of flow of air therethrough substantially ditions are ,compensatedfor by various. ducts or devices in such manner that the fuelbed hasa better opportunity to restore itselfand to be.

maintained in-a more nearly desired average condition. Furthermore, the several duct construe tions are structurally and functionally independent, each including a meter or controlelement in the form of an orifice, the change in. the pressure'difference across which results in change of the associated throttle area in such a direction as to restore the normal differential, and, therefore, the normal rate of fiow. As the orifice is a plain opening into the duct construction and as the throttle and its operating mechanism are en- 7 tirely enclosed within the duct construction without protrusion of moving parts into the air box,

there results an arrangement peculiarly suitable to meet conditions encountered in stoker practice in that derangement of the mechanism on account of ash is reduced to a minimum.

While we have shown our invention in several forms, it will be obvious to those skilled in the art that it is not so'limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and we desire,

" therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What we claim is:

1. In apparatus for supplying air to a flow-resisting bed, means providing an air box supplied with air under desired pressure, a plurality of chambers arranged in a plurality of rows extend- 5. ing transversely of the bed, ducts for supplying air from the chambers to difierent areas of the bed, orifices for admitting air from the box to the chambers, throttles for controlling the flow of air from the chambers and through the ducts to the bed and each throttle including means responsive to differences in air pressure in its associated chamber with respect to air box pressure to control the throttle area, and means providing for area variation of the orifices of the respective rows of chambers to the same extent and of the orifices of the chambers of different rows to different desired extents.

2. In apparatus for supplying air to a flow-resisting bed, means providing an air box supplied with air under suitable pressure, an air chamber, a duct for supplying air from the chamber to the bed, means providing a manometric: body of liquid with one leg portion subject to the air pressure in the chamber and the other leg portion subject to air pressure of the box, an orifice for admitting air from the box to the chamber, and

means providing a throttle controlling the flow of air from the chamber to the bed, said lastnamed means including a float which is moved by changes in liquid level of the leg subject to charn ber pressure to vary the throttle fiovr area.

3. In apparatus for controlling the flow of gaseous medium from a first region maintained under suitable pressure to a second region of variable flow resistance, a duct for supplying gaseous medium to the second region; an orifice for admitting gaseous medium from the first region to the duct; and a throttle having its flow area in the duct and arranged in the path of flow between the orifice and the second region; said throttle including a tubular element forming a part of the fiow passage and having a horizontally disposed lower end, means providing a U-shaped space having a first legwhose upper portion is open to said..fi1ist regionand a second leg whose upper portion isarranged vertically below the lower end of said tubular element and is, .open to the interiorof said duct, andabodyof liquid in said space and whose'level in the second, leg

cooperates with the lower end of .the. tubular element to provide the throttle area.

4. In apparatus for controlling the flow of gaseous medium from a first region maintainedunder suitable pressure to a second region of variable fiow resistance, a duct for supplying gaseous medium to the second region; an orifice for.ad-

mitting gaseous medium from the first. region to the duct; and a throttle having its flow area in the duct and arranged in the path of flow between the orifice and the secondregion; saidthrottle including a tubular element forming a.

part of the fiow passage and having a horizontally-disposed lower end, meansvpr oviding a U shaped space having a first leg Whose upper portion is open to said first region and a second leg whose upper portion is arranged vertically below said lower end of the tubular element and is open.

to the interior of said duct, a body. of liquid in said space, and arfioatsustained by. the liquid in the second leg;, saidfloat cooperating with said lower end of the tubular element to define the throttle area and the levelof liquid in said sec.- ond leg determining the throttle area.

5. In apparatus for controlling the fiow of gas eous medium from a first. region maintained under suitable pressureto second region of variable.

flow resistance, a duct, for supplying gaseous medium to the second region; an orifice for admitting gaseous medium from the first .region to the.

duct; athrottle having its fiow area arranged in the path of flow between the orifice and the second region; said throttleincluding a tubular element forming a part of the how passageand having a horizontally-disposed lower end, means providing a U-shaped space having a first leg whose.

upper portion is opentosaid first regionand a second leg whose upper portiongis arranged vertically below said lower end of the tubular element and is open to the interior of, said duct, and a body of liquid in saidspaceand whose level in the second leg cooperates with the lower end of the. tubular element to .provide the throttle area; and. means providing for adjustment oi the areaof' the orifice.

6. In apparatus, for controlling the flow of gaseous mediumiroma first region maintained under suitable pressure to a second region of variable .fiow resistance; a duct for supplying gaseous medium to thesecondregion; an orifice for admitting gaseous medium from the first region to the duct; a throttle having its flow area arranged in the pathof fiow between. the orifice and the second region; said throttle including a tubular element forming a part of the flow passage and having a horizontallyedisposed lower end, meansproviding a. U-shaped space having a first leg whose upperportion is open to said.

first region and a. second leg Whose upper portion is arranged vertically below said lower end of, the

tubular element and is open at its top to the in-' a ou i m f m a r tr na e e e '15 under suitable pressure to a second region of variable flow resistance; a duct for supplying gaseous medium to the second region; an orifice for admitting gaseous medium from the first region to the duct; a throttle having its flow area arranged in the path of flow between the orifice and the second region; said throttle including a tubular element forming a part of the flow-passage and having a horizontally-disposed lower end, means providing a U-shaped space having a. first leg whose upper portion is open to said first region and a second leg whose upper portion is arranged vertically below said lower end of the tubular element and is open to the interior of said duct, and liquid in said space and cooperating with said tubular element to provide the throttle area, said orifice being arranged above the liquid in order that the latter may be subject to the differential pressure across the orifice to control the throttle area; means for supplying liquid to said space; and a vertically adjustable overflow associated with the first leg for discharging excess liquid from said space.

8. In apparatus for controlling the flow of gaseous medium from a first region maintained under suitable pressure to a second region 01' variable flow resistance, a duct for supplying gaseous medium to the second region and having a chamber at its inlet end; an orifice for admitting gaseous medium from the first region to the chamber; means providing a throttle in the chamber and comprising a vertically disposed tubular element forming a portion of the flow passage for gaseous medium and a body of liquid whose upper surface is normally spaced from the lower end of the tubular element to define the throttle area; and means responsive to difierential pressure across the orifice for controlling the level of said liquid.

ROBERT A. FORESMAN. DONALD J. MOSSHART. 

